Particulate sampling system having flow check device

Abstract

A particulate sampling system is disclosed. The particulate sampling system may include an exhaust sampling unit and a dilution flow assembly to supply dilution air to the exhaust sampling unit. The particulate sampling system may also include a total flow assembly to receive dilution air and exhaust. The particulate sampling system may further include a flow regulation assembly configured to control flow rates in the dilution flow assembly and the total flow assembly. The particulate sampling system may also include a flow check assembly configured to measure the accuracy of the flow regulation assembly.

1. A particulate sampling system comprising:
 an exhaust sampling unit configured to receive exhaust; 
 a dilution flow assembly located upstream of the exhaust sampling unit and configured to supply dilution air to the exhaust sampling unit; 
 a total flow assembly located downstream of the exhaust sampling unit and configured to receive dilution air and exhaust; 
 a flow regulation assembly configured to control flow rates in the dilution flow assembly and the total flow assembly; and 
 a flow check assembly configured to measure the accuracy of the flow regulation assembly. 
 
   
   
     2. The system of  claim 1 , including a bypass disposed between the dilution flow assembly and the total flow assembly, the bypass configured to selectively bypass dilution air around the exhaust sampling unit to the total flow assembly. 
   
   
     3. The system of  claim 2 , wherein the flow check assembly includes an air line configured to supply air to the total flow assembly when bypassing. 
   
   
     4. The system of  claim 3 , wherein the flow check assembly includes a flow check valve configured to selectively block the air. 
   
   
     5. The system of  claim 3 , wherein the flow check assembly includes a flow meter configured to measure an air flow rate. 
   
   
     6. The system of  claim 1 , wherein the flow regulation assembly is configured to selectively pass a first predetermined flow rate of dilution air through the dilution flow assembly and a second predetermined flow rate of diluted exhaust through the total flow assembly, the difference between the first predetermined flow rate and the second predetermined flow rate used to determine an exhaust flow rate. 
   
   
     7. The system of  claim 6 , including:
 a controller in communication with the flow regulation assembly and the flow check assembly, the controller configured to calculate the difference between the determined exhaust flow rate and the measured air flow rate to obtain an error value. 
 
   
   
     8. The system of  claim 7 , wherein the controller automatically adjusts the flow regulation assembly in response to the error value exceeding a predetermined value. 
   
   
     9. The system of  claim 7 , wherein the controller enters an automatic fault condition in response to the error value exceeding a predetermined value. 
   
   
     10. The system of  claim 1 , wherein the flow regulation assembly includes:
 a first flow regulator operatively connected to the dilution flow assembly; 
 a second flow regulator operatively connected to the total flow assembly; and 
 a vacuum pump operatively connected to the total flow assembly. 
 
   
   
     11. The system of  claim 10 , wherein the first flow regulator includes:
 a dilution flow meter; and 
 a dilution air control valve. 
 
   
   
     12. The system of  claim 10 , wherein the second flow regulator includes:
 a total flow control valve; and 
 a total flow meter. 
 
   
   
     13. The system of  claim 1 , including a leak check mechanism configured to separately isolate and pressurize the dilution flow assembly and the total flow assembly. 
   
   
     14. The system of  claim 13 , wherein the leak check mechanism includes:
 a pressure control valve operatively connected to the dilution flow assembly; and 
 a leak check valve operatively connected to the total flow assembly. 
 
   
   
     15. A method for determining the concentration of particles in an exhaust gas, comprising:
 passing exhaust to an exhaust sampling unit; 
 passing dilution air through a dilution flow assembly at a first predetermined flow rate using a flow regulation assembly; 
 passing diluted exhaust through a total flow assembly at a second predetermined flow rate using the flow regulation assembly; 
 comparing the first predetermined flow rate to the second predetermined flow rate to determine an exhaust flow rate; 
 selectively bypassing the dilution air around the exhaust sampling unit to the total flow assembly; 
 allowing air to flow into the total flow assembly while bypassing; 
 measuring an air flow rate; and 
 comparing the determined exhaust flow rate and the measured air flow rate to check the accuracy of the determined exhaust flow rate. 
 
   
   
     16. The method of  claim 15 , including:
 passing the diluted exhaust gas through a filter to remove particulate matter; 
 measuring the amount of particulate matter captured in the filter; and 
 determining the concentration of particulate matter in the exhaust by relating the amount of particulate matter captured in the filter to the determined exhaust flow rate. 
 
   
   
     17. The method of  claim 15 , including:
 calculating the difference between the determined exhaust flow rate and the measured air flow rate to obtain an error value. 
 
   
   
     18. The method of  claim 17 , including:
 offsetting the determined exhaust flow rate by the error value. 
 
   
   
     19. The method of  claim 17 , including:
 automatically adjusting the flow regulation assembly in response to the error value. 
 
   
   
     20. The method of  claim 19 , including adjusting at least one flow measurement device. 
   
   
     21. The method of  claim 19 , including adjusting at least one of a control valve and a vacuum pump. 
   
   
     22. The method of  claim 17 , including:
 automatically generating a fault condition if the error value exceeds a predetermined value. 
 
   
   
     23. An engine test cell comprising:
 an internal combustion engine; 
 an air supply unit configured to provide air to the internal combustion engine during testing of the internal combustion engine in the engine test cell; 
 an engine air intake operatively connected to the internal combustion engine; 
 at least one conduit to channel air from the air supply unit to the engine air intake; 
 an engine stack to channel exhaust away from the internal combustion engine; and 
 a particulate sampling system operatively connected to the engine stack, comprising: 
 an exhaust sampling unit configured to receive exhaust; 
 a dilution flow assembly located upstream of the exhaust sampling unit and configured to supply dilution air to the exhaust sampling unit; 
 a total flow assembly located downstream of the exhaust sampling unit and configured to receive dilution air and exhaust; 
 a flow regulation assembly configured to control flow rates in the dilution flow assembly and the total flow assembly; and 
 a flow check assembly configured to measure the accuracy of the flow regulation assembly. 
 
   
   
     24. The engine test cell of  claim 23 , wherein the particulate sampling system includes:
 a bypass disposed between the dilution flow assembly and the total flow assembly, the bypass configured to selectively bypass dilution air around the exhaust sampling unit to the total flow assembly. 
 
   
   
     25. The system of  claim 24 , wherein the flow check assembly includes:
 an air line configured to supply air to the total flow assembly when bypassing; 
 a flow check valve configured to selectively block the air; and 
 a flow meter configured to measure an air flow rate. 
 
   
   
     26. The system of  claim 1 , wherein the exhaust sampling unit is configured to receive exhaust from an engine assembly external to the particulate sampling system. 
   
   
     27. The method of  claim 15 , where passing exhaust to an exhaust sampling unit includes passing exhaust from an engine assembly to the exhaust sampling unit located externally of the engine assembly.